A radio-frequency (RF) choke, commonly used in cable-television (CATV) networks, allow allows high alternating current (AC) of 10-20 A, 50-60 Hz to pass through, while keeping the impact on the RF transmission chain (such as CATV RF transmission chain) minimal. Such impact is defined by transmission and reflection losses in the RF frequency band of the network. The transmission and reflection losses should be kept substantially constant across the working frequency band of the network. In other words, the transmission and reflection losses should have substantially flat response curve. These response curves should ideally be kept substantially flat for any bandwidth extension within the desired working range of frequencies.
CATV networks typically distribute RF signals in the legacy 5 MHz to 1 GHz range. Prior art high current RF chokes used for these networks typically resonate at frequencies just above 1 GHz. This phenomenon limits the operating frequency of these chokes to about 1 GHz.
A currently available method for frequency bandwidth extension of high current RF chokes includes sophisticated wounding of copper wire on a special constructed ferrite core with special properties. This method can extend the working frequency range up to 1.4 GHz when copper wire having diameter of 1.5 mm is used.
Another solution involves using a low pass filter for blocking RF signals above 1 GHz from getting to the RF choke as described for example in U.S. Pat. No. 7,138,886. Implementing the second method can achieve much higher frequencies but requires diplexer with low pass and high pass filters. The design of such systems requires keeping some guard-band frequencies unusable and tuning of such diplexers is complicated and expensive.